package com.scpii.universal.util;

import java.nio.ByteBuffer;
import java.security.MessageDigest;

public class CacheUtil {
	// 十六进制下数字到字符的映射加密
	private final static String[] hexDigits = { "0", "1", "2", "3", "4", "5",
			"6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };
	public static final String getCachekey(int cmd, byte[] data) {
		
		int len = (data != null && data.length > 0 ? data.length : 0) + 4 + 4;
		byte[] sendbuf = new byte[len];
		h2n_32(sendbuf, len, 0);
		h2n_32(sendbuf, cmd, 4);
		if(data != null && data.length > 0)
		System.arraycopy(data, 0, sendbuf, 8, data.length);
		return MD5.strMD5(sendbuf);
	}
	
	private static final void h2n_32(byte[] dest, int i, int offset)
	{
		ByteBuffer bb = ByteBuffer.allocate(4);
		bb.putInt(i);
		byte[] b = bb.array();
		dest[offset] = b[0];
		dest[offset + 1] = b[1];
		dest[offset + 2] = b[2];
		dest[offset + 3] = b[3];
	}
	
	/** * 把inputString加密 */
	public static String generatePassword(String inputString) {
		return encodeByMD5(inputString);
	}
	
	/** 对字符串进行MD5加密 */
	private static String encodeByMD5(String originString) {
		if (originString != null) {
			try {
				// 创建具有指定算法名称的信息摘�?
				MessageDigest md = MessageDigest.getInstance("MD5");
				// 使用指定的字节数组对摘要进行�?��更新，然后完成摘要计�?
				byte[] results = md.digest(originString.getBytes());
				// 将得到的字节数组变成字符串返�?
				String resultString = byteArrayToHexString(results);
				return resultString.toUpperCase();
			} catch (Exception ex) {
				ex.printStackTrace();
			}
		}
		return null;
	}

	/**
	 * 转换字节数组为十六进制字符串
	 * 
	 * @param 字节数组
	 * @return 十六进制字符串
	 */
	private static String byteArrayToHexString(byte[] b) {
		StringBuffer resultSb = new StringBuffer();
		for (int i = 0; i < b.length; i++) {
			resultSb.append(byteToHexString(b[i]));
		}
		return resultSb.toString();
	}
	/** 将一个字节转化成十六进制形式的字符串 */
	private static String byteToHexString(byte b) {
		int n = b;
		if (n < 0)
			n = 256 + n;
		int d1 = n / 16;
		int d2 = n % 16;
		return hexDigits[d1] + hexDigits[d2];
	}
	
}
